High tension circuit breaker system



June 24, 1958 F. A. cRosKEY- E 2,840,658

HIGH TENSION CIRCUIT BREAKER SYSTEM Original Filed Oct. 4, 1954 2 Sheets-Sheet 1 y, i A/R SUPPZV l INVENTORS ATTORNEY June 24, 1958 F. A. CROSKEY HAL HIGH TENSION CIRCUIT BREAKER SYSTEM 2 Sheets-Sheet 2 Original Filed Oct. 4, 1954 INVENTORS BY I!!! z z ATTORNEY United States Patent HIGH TENSION CIRCUIT BREAKER SYSTEM 1 Frank A. Croskey, New Baltimore, and Charles Derwood Tuttle, Wyandotte, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application October 4, 1954, Serial No. 459,968. Divided and this application December 1, 1955, Serial No. 550,425

4 Claims. (Cl. 200-82) This invention relates to a high tension circuit breaker and associated control therefor that is specially, though not exclusively, suited for use with electrostatic charging apparatus for charging particles of coating material.

The invention is shown in an electrostatic coating installation claimed in application S. N. 459,968, filed October 4, 1954, of which the present application is a division.

The invention has for an object to provide an improved form of high tension breaker and remote operated control therefor specially suited for use with high tension power supplies as are employed in electrostatic coating installations and which features special provisions for efiicient operation of the system and adequate safeguards to protect the operator from the hazards incident to manual operation of devices of this character.

The above and other objects, together with the features and advantages attending the present invention, will appear more fully from the following detailed description and drawings wherein:

Fig. l is a schematic and diagrammatic illustration of a circuit breaker and associated control in accordance with the present invention for an electrostatic spray painting installation;

Fig. 2 illustrates a spray gun and a form of electrostatic paint charging system including a portion of the control apparatus of the present invention;

Fig. 3 is a sectional elevation view of an electric circuit breaker in accordance with the present invention; and

Fig. 4 is a transverse view taken in the direction 4-4 of Fig. 3.

Referring to Fig. l of the drawings, there is shown a high voltage power supply unit 10, which is energized from a local alternating current source of supply over conductors 12 and 14. The output of the power supply may be in the order of, say, 40 kilovolts, and is applied over cable 16 through an air actuated circuit breaker, indicated generally at 18, to cable 20. Cable 20 is connected to one of the charging electrodes of an electrostatic spray painting charging system 22, the other element of which is connected back to the power supply unit over conductor 24. The power supply unit may be of the R. F. oscillator type shown in copending United States application, Serial No. 234,312, filed June 29, 1951, now Patent No. 2,767,359, issued October 16, 1956, in the names of Grayland T. Larsen and Arthur T. Lausten, assigned to the present assignee, and is preferably provided With the current limiting are preventing feature of that application.

The circuit breaker 18 comprises, in general, a stationary high voltage contact 28, a double-ended piston or slide rod 30, a conducting cylinder 32 that surrounds the piston and a ground stop contact 34 which is connected to ground over conductor 36. The piston 30 is actuated from a source 41 of compressed air supplied through an airline 40 to a solenoid-actuatedair valve 42 through which the air is selectively appliedto either one of a pair of airlines 44 and 46 that communicate with the cylinder 32 on opposite sides of the piston 30.

The valve 42 is actuated by a low voltage split solenoid coil 48 which is selectively electrically energized over conductors 50 and 52 through the contacts of a low voltage control relay 54 from a step-down transformer 56 connected to the local alternating current supply. A jumper (not shown) within the housing of the power supply unit 10 connects line conductors 12, 14 to conductors 57, 58, which are shown connected to the primary winding 59 of the step-down transformer 56, the high or ungrounded side of the low voltage secondary winding 60 of which is shown connected to the branched solenoid conductors 50 and 52 through a normally open set of contacts 61 and a normally closed set of contacts 62 of the control relay 54. One side of the actuating coil 64 of the control relay 54 is connected in an energizing circuit which includes conductor 66 connected to the positive six-volt side of the filament of one of the low voltage operating tubes, such as the oscillator tube 68, contained within the power supply 10. The other side of the control relay coil is connected by conductor 70 to ground through a micro-switch 72 that is mounted on the handle of the spray gun 74 grasped by the operator. A pilot light 75 may be connected across the actuating coil of the control relay to indicate the closed condition of the switch 72, which may be of the common snap-action over-center variety.

The spray gun shown in Fig. 2 is of a common commercially available variety and is provided with a handle 76 and a manually operated trigger 77 that is pivotally mounted on a pivot shaft 78 which passes through the body of the gun. Trigger 77 actuates a needle valve 79 contained within the gun and simultaneously controls the flow of atomizing air and paint which are admitted to the gun through the air and the paint supply lines 80, and 81, respectively. The paint or coating material is ejected in particle form from the nozzle or spray tip 82 of the gun which may be grounded.

The pivot shaft 78 for the gun trigger 77 mounts a cam 84 thereon which actuates the movable actuating ele ment 86 of the micro-switch 72 also mounted on the gun, whereby both the flow of the material to be deposited and the operation of the circuit breaker 18 are controlled from a common operating source. The cam 84 is adjustable and may be so mounted on pivot shaft 78 relative to the actuating element 86 of the micro-switch as to actuate the latter upon the initial movement of trigger 77 to cause the application of the high tension voltage to the electrodes of the particle charging system slightly in advance of the commencement of the flow of the particle spray from the gun.

As best shown in Fig. 2, the nozzle end of the spray gun extends through an opening in an insulating shield 90, which is detachably secured to the gun and located between the handle and the spray tip thereof. Fastened I to one edge of the shield and extending in the forward direction of the spray from the gun is a broad flattened current collector electrode 94 which constitutes one of the electrodes of a portable electrostatic charger system. The other electrode is constituted by a plurality of elongated attenuated or needle-like discharge electrodes 96 which are spaced from and are contained in a transverse plane extending generally normal to the collector electrode and to the direction of the particle travel from the gun, which may be connected to ground as shown in Fig. 1. The needle electrodes are mounted in a suitable support 98, shown carried by and extending forwardly of the shield 90, and are adapted to be connected to the high tension breaker cable 20. Cable 20 may be of the rubber-covered coaxial variety and is brought into the charging system for connection to the discharge electrodes rearwardly-of the-gun-toprevent the cable from being coated with paint from the gun. Conductor 24 may. be a rubber-covered, braided conductor that connects collectofplate "94'back tothepowersupply unit 10*and maybeat "or a few volts above .ground'po'tential.

'The'application of a high difference of potential 'between the discharge'needles and the collector electrode effectively ionizes the atmosphere therebetween, causing an electric wind in the form of a corona point discharge to emanate from the discharge needles. This discharge extends a short distance from the needles-toward but less than'the distance fromthe tips of the needles to the collector electrode-and efiectivelyplace's a very high charge concentration on the surface of the particles of coating material. This charge is substantially constant and independent of the location of the spray gun from the articles tobe coated.

The breaker'18 of the present invention is shown more fully in Figs. 3 and 4 and comprises a cabinet housing 110 containing a plurality of spaced support blocks 112, 114,116, 118 which are mounted on the base 120 of the housing, substantially as shown. The support blocks are composed of suitable insulating material such as Polysterene. Monted in an end wall'122 of the breaker housingis a coaxial cable connector 124 for the coaxial cable 16 from the power supply unit 10. The end of the connector within the housing receives one end of a Polysterene tube 126, the other end of which is seated in a shallow counterbore provided on one face of the block 118. Tube 126 surrounds a central conductor 128 whichis connected at one end of the central conductor of the cable 16 and has a banana-type connector plug 130 at the other end thereof contained within a bore extending through block 118. Plug 130 cooperates with a mating jack 132, one end of which is threadably received within a threaded bore on the side of block 118 and whose other end is received in a Polysterene tube 134 Which. is seated in shallow counterbores provided in the adjacent faces of blocks 116 and 118, as shown. Thehigh voltage contact 28 of the circuit breaker is contained within tube 134 and is spaced from jack-132 by spring 136, and' is adapted to contact one end 138 of the piston 30. The end 138 of the piston 30 extends through a bore in block 116 and into the bored tube 134, substantially-as shown. 7

The opposite ends of the conducting cylinder 32 in which the piston 30 is contained are seated in annular grooves provided in adjacent faces of support blocks 114, 116. Piston 30 is shown as having an enlarged central portion 30a, which is piloted within the cylinder 32, and a reducedend portion 140 which is adapted to enter and slide in a bore :extending through block 114.. Seated in shallow counterbores formed in adjacent faces of blocks 114 and 112 is another Polysterene tube.144 which mounts the spring biased ground contact 34 that is connected to ground over conducting bus 36. The-support blocks and tubes of the breaker assembly are rigidly secured together as by tie bolts 148 and 149.

The wall150 of the breaker housing 110 receives the air inlet line '40 through an opening therein adjacent the inlet to the air valve 42, which may be a type EV- A .Electroaire four-way valve operated from a 110 V-lOV step-down transformer such as is manufactured by the Bellows Manufacturing Company of Akron, Ohio. Thetwo'outlets of the 'valve are connected by appropriate lengths of rubber hose'or flexible tubing 44 and 46 toopenings 154an'd 156 in the cylinder 32 on'opposite sides of the piston 30. The-air inlet line 40 may be provided with an'appropriate shut-off cock valve, filter, pres sure reducer,pressure gaugeand lubricator' in accordancewithconv'entional practice.

fAs"shown in'Fig. .4, the "cylinder 32 is conductively connected by a banana-plug and jack 160 to a conductor 162, which extends centrally through a Polysteren'e tube 4 '164and is connectedto 'a coaxial cable connector1-66 contained in the front wall-168 of the cabinet housing. Connector 166 is connectedto the coaxial cable leading rcarwardly to the needle;li ke discharge electrodes 96 of the charging syste'rnllocated at the gun.

In the operation of the system, inward movement of the trigger 77 by the operator initiates the flow of paint in'atomi-Ze'd spray form from the gun'and completes an energizing circuit for the coil'64 of the control relay:54 from the low voltagesection of the power supply. Energization of the relay closes contact 61 and opens contact 62 thereof :to complete a low voltage-energizing circuit from the secondary of transformer 56 overconductor 50 to the advance coil or upper section of-the solenoid 48 in valve 42. Valve 42 is :then actuated to supply air from inlet line 40 to air hose 44 communicating with the left side of the piston 30 in the cylinder 32 and causes the piston to move rapidly to the right to engage the high voltage contact'28. 'Thiscompletes the'highpotential circuit for the electrodes of the particle charging system from the output of the power supply 10, conductor'16, breaker contact 28, piston '30, c'ylinder'32, coaxial cable 20, the discharge needles 96, the ionized zone between discharge needles and the collector plate 94, and back to the power supply over conductor '24. When the trigger of the spray gun is released, the actuating coil of relay 54 is de-energized, which causes relay contacts 61 to open arid contacts 62 to close, the latter establishing an energizing circuit for the retract or lower section ofthe solenoid coil 42. Air is then supplied over hose 46 to the right side of the breaker piston which then .movesto the left to break the circuit'at contact 28.

Since the coaxial cable 20 from the breaker to the discharge electrodes of the particle charging system carried by the spray gun may be of considerable length, a sub stantial amount of high potential energy will be stored within the coaxial cable by the capacitance eif ect thereof This energy will remain on the cable for some timeeven after the system has been disconnected from the v. line. So that'the operator'may safely handle the electrodes, as for example when it is desired to disassemble the charger from the gun for cleaning after a period v of use, the breaker of the present invention providesfor rapid dissipation of the energy stored on the cable by connecting the cable 20 to ground through the cylinder 32, piston 30 and ground contact 34 when the trigger 77 is released.

It will be noted also that theibreaker 18, which is of the S. .P. .D. .T. variety, is.located in the output of the high tension power supplylti and that its operation will-not afi'ect'the condition of energization of. the power supply which will be ready to deliver its full-rated output .at all times. The system thus differs from those installations in which the entire power supply unit is de-energized to control the applicationandinterruption of thehigh ten sion voltage to the electrodes of the charging or deposit ing'system.

By disposing the contacts 28 and 34 within the bores of the plastic'tubes 134, 144 in which are also received the ends of the piston,-the high-tension breaker points are completely surrounded with plastic or electrically 11011 conductive material so'any arcing caused by the closing or opening of the switching contacts will be'completely confined'within the bores of the tubes and there will be no possibility of flashbores to the metallic cabinet or housing.

Although aspecific embodiment of the inventionhas been shown and described, it will be understood that it is but illustrativev and that various modifications may be made therein'without' departing from the scope andspirit of this invention. I i "What is claimed is: g V V "'1'. A hightension'circuitbreakersystem for eontrhlling the application and interruption of a high tension voltage from a high tension electrical source adapted to be connected by a coaxial cable to a load comprising, in combination, a pair of spaced electrical contacts, a conducting cylinder including a piston operating member in electrical contact therewith and movable therein between positions in electrical contact with either of said contacts, means for actuating said piston including a source of compressed air, valve means having an inlet connected to said air source and a pair of outlets communicating with said cylinder and operable to admit compressed air to either side of said piston, and control means controlling the operation of said valve means, conductor means connecting one of said electrical contacts to ground, and a coaxial cable connecting the other of said contacts to said high tension electrical source and said conducting cylinder to said load.

2. A high tension circuit breaker system for controlling the application and interruption of a high tension voltage from a high tension electrical source to a load comprising, in combination, an electrically conducting cylinder, a double-ended piston operating member slidable in said cylinder and in electrical contact therewith, a pair of spaced insulating support blocks mounting said cylinder between the adjacent faces thereof, each of said blocks having a bored portion axially aligned with said cylinder and adapted to receive an end of said piston thereof, a separate electrical contact in the bored portion of each of said blocks, means for actuating said piston between positions in electrical contact with either of said contacts including a source of compressed air and control means including valve means connected to said air source and selectively controlling the application of air therefrom to opposite sides of said piston in said cylinder, and con ductor means connecting one of said electrical contacts to said high tension electrical source, the other of said contacts to ground and said conducting cylinder to said load.

3. A high tension circuit breaker system for controlling the application and interruption of a high tension voltage from a high tension electrical source adapted to be connected to a load by a coaxial cable, said system comprising, in combination, a conducting cylinder, a doubleended piston operating member slidable in said cylinder and in electrical contact therewith, a pair of spaced insulating support blocks mounting said cylinder between the adjacent faces thereof, each of said blocks having a bored portion axially aligned with said cylinder and adapted to receive an end of said piston therein, a separate electrical contact in the bored portion of each of said blocks, means for actuating said piston between positions in electrical contact with either of said contacts including a source of compressed air and control means including valve means connected to said air source and selectively controlling the application of air therefrom to opposite sides of said piston in said cylinder, conductor means connecting one of said electrical contacts to ground, and a coaxial cable connecting the other of said contacts to said high tension electrical source and said conducting cylinder to said load.

4. A high tension circuit breaker system for controlling the application and interruption of a high tension voltage from a high tension electrical source to a load having a capacitive characteristic, said system comprising, in combination, a conducting cylinder, a double-ended piston operating member slidable in said cylinder and in electrical contact therewith, a pair of spaced insulating support blocks mounting said cylinder between the adjacent faces thereof, each of said blocks having a bored portion axially aligned with said cylinder and adapted to receive an end of said piston therein, a separate electrical contact in the bored portion of each of said blocks, means for actuating said piston between positions in electrical contact with either of said contacts including a source of compressed air and control means including valve means connected to said air source and selectively controlling the application of air therefrom to opposite sides of said piston in said cylinder, conductor means connecting one of said electrical contacts to ground, a coaxial cable connection from said high tension electrical source to the other of said contacts and a coaxial cable connection from said conducting cylinder to said load.

References Cited in the file of this patent UNITED STATES PATENTS Germany Feb. 18, 1939 

